阅读理解。

     Air is a colorless, tasteless and invisible (无形的)  gas that is around us. An"empty" drinking glass

and an"empty"room,in fact,are not really empty. Each is filled with air. When the glass is filled with

water, the water pushes the air out of the glass.

     Air, as a gas, has no definite (确切的) shape, but because it is matter, it takes up space and it has

weight. It is easy to prove (证明) that air is something that takes up space. Stuff a piece of dry cloth

into the bottom of a glass so that it will not fall out when the glass is turned upside down. Push the

upside-down glass,holding it straight up and down, into a jar of water till the glass is completely covered.

When the glass is taken out of the water, the cloth is still dry. The air inside the glass shows that it takes

up space and keeps the water from coming in.

1. Air has no definite shape because          .

A. it is a mixture      

B. it is a gas      

C. it is matter      

D. it is nothing

2. Since air is matter, it has            .

A. weight        

B. color      

C. taste        

D. shape

3. The word"stuff"in the passage means"         "in Chinese.

A. 撕裂          

B. 遮盖      

C. 取下        

D. 填塞

4. The experiment the writer tells in the passage          .

A. should be carried out in space

B. must be done in the lab

C. can be made in the room

D. only can be done in the open air

5. Which of the following gives us the correct picture of the experiment?

(W=water   A=air   C=cloth)